Steam turbine lubricating oils



Patented Nov. 16, 1948 S- 'ITATES PATENT yO FFlCE i a i l i i i l i V224542075 :S-TEAM-iTU-RBiNE LUBRICATING OILS Robert G. M'astih}Gkmulgee, kla., assignor to fiities s'ervfceflil Gompany, Bartlesville,0kla.,; as: corporation-i rof'lii'elaware NoDrawii1g.., ApplicationApril 2119M; S'eri'aI No. 738,933

, My iirvention' reiatesto improvementsin lubri eating; oilsaridi moreparticularly to-"an improved steam: turbine; lubricating oil compositioncomprising .a' mineral]lubrica-ting'oil containing a small? percentageof a pyrazoline compound as an oxidatimrinhibitbr. J

Steam turbine "oils" are used under conditions which; are verysevereas'far asroxid'ation is concerned because the oil is constantly in contactwith waterrand'f with ste am'; asfwell as beingsubjected'torelativeiyliig'h temp eratures.

The-primary object of my irrvention' is there.- toreto provide an'improved lubricati'ng oil composition which" will be relatively stableunder the operating con'ditions encountered in steam turbineg.

A further object of myi'nvention-is to'providezan improved method oflubricating steam turbines.

Inymx-work' with lubricating oils; Ihave discoveredthat'aminerallubricating oil' ofa grade" suitable' ior lubricating steam turbinescontaining; a small" percentage ofan oil'soluble' organic 'pylazolinewill-be inhibited again-st oxidation'f'or lon periods oftim'e. Thesecompounds all contain the pyraizoline ringwhich is a; five 'memberedring containing two nitrogen atoms' linked" together and tea chainofithree'cavbon atoms.

In" accordance with a preferredform' of my: inverrtion, I "employapyrazol-ine compound containing substituents on two .or more positionsof the yraaoiinering; and particularly select such sub stituent's sothat the" resulting compound-antioxideiitfwi-ll be solublein the minerallubricating oil stock a-ndj' Wi11"not be {removed to anyappreciableextent by being brought in contact with-water and steam; Y

The features-of my invention may be illustrated; in; connectionwithcertainspecifi c examples sl'row'ing-theeffectiveness of certainpyrazolines in" turbine oils.

Ewample firthis' example two petroleum oil stocks were 'tested inaccordance with the standard oxidation testing procedure for steamturbine oils (Proc. Am. Soc. Test. Mat,, 1943, p.275 etseq) Oil A was asolvent refined neutral oil having a Saybolt universakviscosity of 150:at"1 00'F!; Oil B'was' an acid refined neutral oil having asayboltruniversal viscosity of 200 atlOOi F. t i

In the table below the induction periods for these' oi l's are givenwhen uninhibited against oxielation amLwhen inhibited with: various"percentages of tlzreip'yrazoline compound, 1-phenyl+3',5,5- trimethylpyrazolinev fi elaiimsn (01. 252-50) -Hcuss-Induction erio Oil A Oil BUninhihH-pWni-h TM '5; v Temp 180 Oi]+0.25% Pyrazoli 1e compouud 6001,440 0il l-0.50%'Pyrazo line=compmmd B000 2400 O1l+l-.0%- Pyrazolmecompound-m 2, 000 3, 500

. It will: noted-- that the. 1 particular pYrazel-ine compound usedinithese tests was- .much more eie fectivegwithithe-i-acid refined:neutral OHLthQI-I it was: with; the; solventixrefinedgoilm Howeven theefi'ectiwenesstisi-veryz considerabler-whenit isznoted thatbvvusing=.on-1y;1 of theipyrazoline the induction period was extendedfromal-hol1rsfor the uninhibited oil to 2,000 hours.

Example II In this instance the-same'pils as tested in Example I hadincorporated in them an appropriate percentage of the pyrazolinecompound, l-phenyl- 3-isobuteny1-5,5-dimethyl pyrazoline. The re- -vsults were as follows?" Hours-Induction Period Uninhibited oil QOiI-l'-0.50% 'Pyrazo 1ine compound;v 2, 200 O11+l.0%iPyrazolmecornpoundnn 2,

a i In these-tests: the lower percentage of: inhibitorWESEDO'ETHSBdlWiifihOiTAL a i 1 i The: ;u-se1=of the: pyrazolinercompound inhibitors found it'o. :haververy little; eifec tin.changing-the other-"properties,- of the oils-tested, for example;the-acid color; .gra.vity andpoun point-re.- mained substantiallyunchanged by the-v. addition of: 13%: oaist'he pyrazoline The flash,-fire a-nct ViS: cnsfizies? were: lowered slightlst while thevsteamemulsionnumber-went-upsomewhat; i'

p discovery of the usefmnesssofzthe pyrazoline compoundsasr oxidationinhibitors for lubricating oilisiarrd particularl tiorrsteam-tin'bineoils is-based my coneepti'om that pyrazoline: compounds eontairringrthe.pyrazole ring; would be-efiective; as antioxidizi-ng agents=; 'Iihe:str-ucturezofzthissring, isiweil known: and may be-zindieated as tollowThe positions of the various elements in the ring are indicated bynumbers, and accordingly, the pyrazolines referred to in the foregoingexamples have the following structures in which it will be seen that thecarbon atoms in the pyrazole ring are saturated:

1-phenyl-3,5,5-trimethyl pyrazoline 1-phenyl-3-isobutenyl-5,5-dimethylpyrazoline My conception that the pyrazole ring was theeffective part ofthe pyrazolines was supported by tests which showed that the varioushydrocarbon substituents upon the ring were ineffective in themselves asoxidation inhibitors.

In accordance with my invention it is to be understood that thepyrazolines may have various hydrocarbon substituents'or radicals on thepyrazole ring, and therefore the compound may have the general formulaRI! R t C-C-R in which, B may be an aliphatic or an aromatic group, R, ahydrogen or an aliphatic or an aromatic group, and R," is preferably anaromatic group but may be an aromatic or an aliphatic group. R. ispreferably hydrogen.

Various methods are known for the preparation of pyrazoline compounds,but I have found the following general method effective and to give highyields. For example, 1-phenyl-3,5,5-trimethyl pyrazoline is prepared bymixing 108 parts by weight of phenylhydrazine with 120 parts by weightof mesityl oxide in a suitable still equipped with a refluxingarrangement. These proportions provide an excess of the oxide so as touse up substantially all of the phenylhydrazine, the surplus beingrecovered for use in succeeding operations. A 50-50 mixture of ethylalcohol and acetic acid is added to the still, as for example about 25parts byweight, and the mixture is refluxed for about 2 hours which isusually sufiicient to complete the action. Thereafter, the mixture isvacuum distilled to remove the alcohol, water, acetic acid and theexcess of mesityl oxide. At 12 millimeters of mercury pressure theportion distilling between 150 C. and 170 C. is recovered as thepyrazoline product. In one operation this corresponded with about 90% ofthe theoretic yield and the product having this wide boiling range ofabout 20 C. was found to be as effective as an 1 cut oils.

turbine lubricating oils, but it is to be understood 1 that they may beused in other mineral or petroleum lubricating oil stocks, and inconjunction with an antirust agent.

The oil stocks A and B described above and containing suitableproportions of a pyrazoline inhibitor are steam turbine lubricating oilstocks and effectively serve that purpose in lubricating steam turbinesfor long periods of time without being oxidized to any appreciableextent. 1 In fact, in most cases the actual service given by these oilsmaterially exceeds thatindicated by the tests, since, as is wellunderstood, the conditions of such tests are more severe than theconditions to which the oil is subjected in the steam turbine. Whilethepyrazoline compounds referred to are readily soluble in the steamturbine stocks and other mineral oils, and may be mixeddirectlytherewith, they may be first dissolved in a base oil stock to provided aconcentrated solution containing, for example, from 25 to 50% of theoxi-' dation inhibitor, and this concentrated solution oxidation.

. What I claim as new is: r

1. A steam turbine oil composition comprising a refined mineral steamturbine lubricating oil having incorporated therein an antioxidantselected from the group consisting of 1-phenyl- 3,5,5-trimethylpyrazoline and 1-phenyl-3-isobutenyl-5,5-dimethyl pyrazoline.

2. A steam turbine oil composition comprising a refined mineral steamturbine oil having incorporated therein an antioxidant in sufficientpro-. portion to effectively inhibit the oxidation of the oil for asubstantial period of time, said antioxidant comprising1-phenyl-3,5,5-trimethyl py-. razoline. f i 3. A steam turbine oilcomposition as defined by claim 2 in which the composition containsfrom,0.50% to 1.0% of the oxidation inhibitor. 7 4. A steam turbine oilcomposition comprising a refined mineral steamturbine oil havingincorporated therein an antioxidant in sufficient proportion toeffectively inhibitthe oxidation of the oil for a substantial period oftime, said antioxidant comprising 1-phenyl-3-isobutenyl-5,5-di methylpyrazoline.

5. A steam turbine oil composition as defined by claim 4 in which thecomposition contains from 0.50 per cent to 1.0 per cent of the oxidationinhibitor. I

ROBERT G. MASTINL REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,316,587 Irigai Apr. 13, 19432,214,152 Wilkes Sept. 10, 1940 1,805,953 Morton May, 19, 1931-

